Hi , i have a couple of projects that im working on low power , and want to use a PC ATX psu to drive them.
Using the 12v rail from one of the molex connectors i get 12v , but i need to drive the arduino board 9v from it any help?
Whats the best way of doing this?
Similarly , 12v from a car cigarette lighter to power 12v and a 9v arduino supply?
Any Advise?
Cheers
The arduino will run quite happily from a 12 volt supply, so why do you want 9 volts. If you really do want 9 then use a simple voltage regulator such as an LM7809
i have a Arudino Mega ,thought the socket was 9v , my mistake.
It was not just for the arduino i was looking for some other stuff that using 9v psu's to save having several , just run them off one big psu etc
Cheers
Get a switching power supply from places like pololu.com to efficiently convert your 12 to 14v+ input down to 5V or 9V ...
CrossRoads:
Get a switching power supply from places like pololu.com to efficiently convert your 12 to 14v+ input down to 5V or 9V ...
Well, he's already using a PC ATX power supply - it has a regulated 5VDC output (or it should) - so...
Also - the LM7805 needs about 7 volts (7.2 volts based on this datasheet: http://www.national.com/ds/LM/LM341.pdf) to maintain regulation; maybe you could use the 5V rail as "ground" and the 12V rail as the positive rail - leaving you with 7 volts...
Not sure how well this would play with other items - but I know that is one way to get 7 volts from a PC supply...
Personally, I think bypassing the regulator and using the 5V rail from the power supply is the best bet.
That's good for 5V, still need a regulator for 9V for the other circuit mentioned.
12 volt DC Input PC ATX-12 Style Power Supplies. DC Input ATX style power supply, 24 volts input, DC Input ATX-12 Style power supplies ...
maybe you could use the 5V rail as "ground" and the 12V rail as the positive rail - leaving you with 7 volts...
No, that's not going to work, voltage regulators only source current on their outputs, they can't sink it.
It actually works quite well, lots of computer enthusiasts do just that with fans to run them at a slower (and quieter) speed.
It only works if something is there to sink the current - for a SMPS that means it uses active commutation rather than schottky diodes - you may be lucky, but it's not something the PSU was spec'd for.